


Twincest: Kagamine Style

by Chozin_Yi



Category: Vocaloid
Genre: 69 (Sex Position), Cowgirl Position, Cross-Posted on FanFiction.Net, Doggy Style, F/M, First Time Blow Jobs, Lemon, Missionary Position, Sexual Experimentation, Shameless Smut, Shower Sex, Spooning, Twincest, Vaginal Sex, cross - Freeform
Language: English
Status: Completed
Published: 2018-05-22
Updated: 2018-05-22
Packaged: 2019-05-10 05:00:26
Rating: Explicit
Warnings: Underage
Chapters: 3
Words: 4,979
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14730425
Author URL: https://archiveofourown.org/users/Chozin_Yi/pseuds/Chozin_Yi
Summary: After a day Of experimenting with each other, Rin and Len undergo a change, from Curious teenagers to complete Nymphomaniacs! (Lemon Warning)





	1. Chapter 1

**Author's Note:**

> This story is also posted on FanFiction.

Chapter Summary: Rin has always been asking some of the weirdest questions, but this one might take the cake, and Len's virginity.

Chapter 1: One morning, an awkward request leads to incest.

It was Sunday morning and the Kagamine twins woke up to the sound of the birds singing. Rin Kagamine opened her eyes, sat up, yawned, and stretched her arms before climbing out of bed and went to her closet to change into her clothes for the day. Len Kagamine meanwhile, groaned into his pillow, dragged himself out of bed, and walked out of his room to the bathroom, not bothering to change his own clothes. Rin went downstairs and began to prepare breakfast for herself and her brother. She threw bacon into one pan and as it sizzled, she poured pancake batter into a separate pan. After finishing his business in the bathroom, Len sauntered downstairs slouching, and took his seat at the table.   
"Len, shouldn't you be dressed already?" Rin said to him, tipping bacon onto his plate. "For what? It's Sunday, and it's not like we have any plans today." Len retorted as he poured syrup on his pancakes. "Well, that doesn't mean you can walk around in your night clothes all day. And besides, (She sniffed the air near her brother) you reek!" Rin said, pinching her nose. Len just rolled his eyes and replied "Fine, just lemme eat first." with his mouth full of bacon. Rin sighed and took her seat at the table and began to indulge in her pancakes. The twins ate their breakfast silently, and when they had finished, Len got up and headed upstairs to hit the shower while Rin put the dishes and silverware in the dishwasher. As a cascade of water ran down Len's back, he was beginning to shampoo his blonde hair, when he realized that he forgot to get a spare set of clothes to change into. "Aw crap..." He grumbled to himself. "Rin!" He called. The blonde twin in question heard her brother's calling over the rushing water and headed upstairs to see what he needed. "What is it Len?" She asked as she poked her head into the steamy room. After rinsing his hair, Len peaked around the shower curtain to his sister. "I forgot to grab some clothes, could you get some for me?" He asked over the downpour. "Kay." She replied and went to Len's room. After grabbing one of Len's shirts and a pair of shorts, she peaked back into the bathroom. "Do you want me to leave them here or in your room?" Rin called to him. "You can just leave them in my room." Her brother replied. "Alright." She said nodding her head and shutting the door. Leaving the clothes on the bed, she walked over to her room next door to grab her CD player along with a copy of an album from one of her favorite Japanese bands, Bad Religion. As the blonde girl ventured to her room, Len shut off the shower and climbed out to dry up. Satisfied and thinking he was sufficiently dry enough, Len wrapped his towel around his waist and peaked out into hallway. Seeing that the door to Rin's room was closed, Len felt the coast was clear and walked to his own. Removing the towel, he was about to dress himself, but realized that Rin forgot something. "Aw man, she forgot to get me a new pair of underwear." Len tsked to himself and walked to his dresser before opening a drawer and grabbed a pair of boxers before sliding them on. He then took the shorts and slid into them before pulling the shirt on, now fully clothed. He turned to leave but saw his sister standing in the doorway, holding her CD player. "Rin?" Len said raising his eyebrow. It then occurs to Len that he left the door wide open, and judging by the blush on Rin's face, she had seen Len in all his glory. "Oh no! Uh, Rin! Forget you saw anything okay!? This never happened! Right? Right!?" Len yelled, blushing madly. Instead of agreeing and apologizing, Rin sat her CD player on Len's desk and shut the door behind her. "Lemme see." She said. "Excuse me?" Len replied, believing his ears were playing tricks on him. "You heard me. Take 'em off, I wanna see you again!" Rin explained bluntly. "W-why?! Why do you want to see me naked? I'm your brother!" Len yelled, daring to believe what's transpiring right now. "Len, how long has it been since we last saw each other naked?" Rin inquired. "Not since we were toddlers when we used to bathe together. But why are so... 'interested' all of a sudden." He replied, leering at the perverted girl who is his sister. "Because I was too young to be interested back then, but I am now. Besides, I figured it would be easier if it was my brother and not some random boy, right?" She asked, tilting her head with a cute, curious look on her face. "I don't know." Len mumbled, holding his arms behind his back. "How about this, do you wanna see what a girl looks like down there?" Rin questioned. Len looked at her dead on. "Are you really suggesting...?" But before he could finish, Rin piped up. "Yeah, I'll show you mine if you show me yours!" She explained. Len just stared at her, opening and closing his mouth like a fish out of water, at a loss for words. He did overhear other boys at school having hushed conversations about the times they played "I'll show you mine, if you show me yours" with some girls they knew. He thought he'd never have a chance to play it with a girl, not counting Rin of course, but now that he thought about it, Rin's been there his whole life. He even started making sense of Rin's logic about it being easier since they're siblings and they've know each other their whole lives. "Fine, but we do it together, okay?" Len said, his mind made up. Rin smiled and nodded her head. Standing in front of each other, the twins grabbed the waistbands of their shorts and looked at their respective twin's eyes. 

Rin began counting.  
"3"  
Len continued.  
"2"  
Rin finished.  
"1, go!"  
With that, both twins yanked their pants down along their underwear. Len had his eyes shut, but once the deed had been done, he opened them, seeing his sister's face, focused on the now bare area between his legs. Following her example, he slowly looked down and saw something he never thought he'd see again, his sister's bare pussy. Letting out a small gasp in awe, Len took in this beautiful sight. Of course, his hormones began working on overdrive and he realized that his boyhood was starting to stretch and stiffen. He's had erections before, I mean, he's woken up with morning wood numerous time before, but sporting one in front of his sister made his face flush with embarrassment as he pulled the hem of his shirt down to cover it. "Wait! Lemme see!" Rin said as she shook her pants and underwear off her ankles and squatted in front of Len while lifting his shirt back up. "Wow, I didn't know it gets big like that." She said in awe. You see, despite being 14 years old, the twins haven't exactly had proper Sex Education. The bare minimum they knew was that boys and girls had different "equipment" down there, and that they are used for making babies, but they lack any specific details, thanks to their school passing a new rule, that students don't get proper Sex Ed until they're seniors. And even though Len has had erections before, he never really learned about masturbation, so he never actually "relieved" himself before either. His morning wood would usually just go away once he's in the shower. Although that doesn't mean he's never been interested in the opposite sex, he and his sister are in the same room butt naked after all. "Len go lie down on the bed." Rin asked him. "Kay." He replied, sitting on the bed with his back to the headboard. Rin climbed up next to him and kept on staring at his boner like it's some animal she's never seen before. "Can I touch it?" She asked looking up at him. "I guess..." Len mumbled. With 3 fingers, Rin took his penis in her hand, and slowly stroked it, making Len gasp and moan from these foreign sensations. "Wow, it's soft and hard at the same time. And so smooth too!" She said to herself, her excitement building. "Rin, that feels really good." Len said as he took deep breaths. "Does it? Cool!" She said, happy that she's making her brother feel good. "You know, it kinda looks like a funny looking lollipop!" Rin exclaimed, giggling. "In fact..." Without another word, she began to lick up and down the sides of Len's erection causing him to moan in pleasure. "Ah Rin! That's so good! Don't stop!" Len cried out, grabbing a pillow that was next to him and hugging it closely as he watched his sister giving him head. Encouraged by Len's words and wanting to please her brother more, she took him whole in her mouth and sucked harder on his dick, bobbing her head up and down continuously. Len gripped the pillow tighter and moaned loudly, pleasure filling his whole body, while another feeling began to build in his groin. When it was close to its peak, Len gasped out and said "Rin! Stop! I gotta- I gotta pee! Wait! Ahhh!" And with one last gasp, he erupted in Rin's mouth, filling her up and surprising his twin. Out of Instinct, she swallowed the load, and smacked her lips. "What was that stuff? It was salty, but I really liked it." She inquired. Rin then rubbed her finger on his dick, covering it in the last of his seed. "Is this semen?" She asked her brother. "It could be. Oh my god Rin, that was awesome!" Len replied panting. He then looked down to Rin's pussy, and a thought occurs to him. "Rin, here, take my place. I wanna do you now." He said, having her lie down. "Really? Okay!" She said excitedly, as Len spread her legs. Without thinking twice, Len leaned down and began licking all around Rin's vulva and her sweet, untouched lips. "Oh my god! Len that's so good! More! More!" Rin begged. Not needing to be told twice, Len carried on and licked Rin's pussy as it became wet not just with his saliva, but with her juices as well, reaching every angle of her vulva and dipping his tongue into her folds. As he lapped her up, he brushed her clit making Rin scream in intense pleasure. "Oh Len! Do it again! Lick right there! Please!" Rin panted out. Len did as she asked and continued to lick circles around her clit, sometimes even sucking or nibbling on it. Rin eventually hit her peak and screamed in ecstasy from her first orgasm and thrusted her pelvis forward into Len's face. As she came down from her high, Rin caught her breath and sat up to see her brother wiping his mouth with his wrist. "Oh Len! That was the best feeling ever! Thank you!" She said as she hugged her twin closely. "You're welcome Rin." He said happily as he hugged her back. They both looked at each other and without a second thought, they kissed their respective twin deeply, swirling their tongues around and sucking on them. When they both broke for air, Rin looked down to see Len's erection standing tall again. "Looks like you want some more fun." She said giggling. Len nodded. "Hey Rin? I wanna try something different. Can I?" He asked pulling his shirt off. "Okay. Like what?" She replied as he pulled her shirt off as well, exposing her perky A-cup breasts and having her lie down again. Len spread her legs again and this time knelt in between them and rubbed the head of his dick against her entrance. "Do you wanna have sex with me?" She asked realizing what he meant. He nodded. "But won't I get pregnant?" Len shook his head. "I don't think so. Your period wasn't too long ago right?" He asked. Rin nodded. "I think we're good then." Len then took hold of his penis and began to push into his sister's virgin pussy, breaking her hymen and making her scream. "Stop! It hurts!" She cried. Len held himself still as best he could, which is no easy task, as Rin's pussy enveloped his dick. "I think you're good." Rin mumbled. Nodding, Len began to thrust in and out of Rin, making her gasp and moan, feeling her pussy pull and suck him back in with each thrust. "Oh Rin, you're so tight!" Len moaned and he quickened his pace. "Ah! Ah! Ah! Oh Len, you're filling me up and it feels so good!" She moaned as she wrapped her legs around Len's waist, begging him to go faster. Heeding his sister's wish, Len started railing into her as fast as he could. "Len! Len! Len! Len! Oh my god, I'm cumming!!!" Rin screamed when her orgasm hit. The sudden tightness within her pussy was too much, and Len hit his own climax and squirted his spunk deep into her, moaning his twin's name. After his second ejaculation of the day, Len pulled out and hugged his sister closely. "That... was... amazing!" She breathed out. Len couldn't help but smile and kissed his cute sister on the nose. Rin looked down and saw that Len was actually still hard. "Wanna go again?" She asked him. He just grinned and said "You bet!" "Here." She said, rolling themselves over. "Let me do it myself this time." She then straddles him, reaches down and grabs Len's penis, then lowers herself on it, gasping at being filled again. Once she's comfortable, Rin begins to ride Len's boner, bouncing in her seat and moaning his name. Looking up at her, Len reaches up and gropes her boobs and fondles the pale orbs in front of him, occasionally tweaking the nipples, making Rin cry out. "Oh yeah, oh yeah, Len I love your dick!" The blonde girl moaned out. "Rin I love your pussy!" Len moans as the horny sister in front of him bounced faster and faster. Moving his hands down from her breasts, Len began to grope and squeeze her butt, and started thrusting up to meet her hips. Soon their peaks got closer and closer until they both cried "I'm cumming!!!" into the air as they shared their mutual orgasm. Rin lied down on top of Len, resting her head on his chest, panting. Len pulled her close and kept his arms around her back. Without another word, they kissed, and fell asleep.

End of Chapter 1.


	2. Afternoon Of Debauchery

**Summary for the Chapter:**

> Turns out, having sexy time in the morning isn't good enough for these two teens!

Chapter 2: Afternoon of debauchery.

Len opened his eyes slowly, taking in the view of his bedroom ceiling and feeling the weight of his twin sister laying on top of him, her head cradled in his arm's embrace. He smiled to himself, remembering that he and Rin gave their virginitys to each other and softly stroked her hair as he looked over to the digital clock on the nightstand next to his bed, seeing that it read 1:27 P.M. Rin then mumbled something as she began to stir and raised her head, wiping her eyes and looking at her brother below her. "Why good afternoon sunshine. Did you have a nice nap?" Len flirted with a big grin on his face. "Yeah, but only because I'm with you." Rin flirted back as she hugged him close, feeling their naked bodies together. "Len, that was so much fun. You're the best brother ever!" She exclaimed, snuggling him. "Awww, you're so sweet." Len replied before kissing her forehead. Rin smiled and lifted herself up and climbed off him and bed. "I'm going to get a drink." She said. Len leaned up and stared at her cute, tight butt as she walked out of his room and headed downstairs. Smirking, Len sat up and decided to follow after her.   
Reaching the bottom of the stairs, Rin strolled into the kitchen, opened the fridge, feeling the chilly air escape and cover her naked body in goosebumps before grabbing a water bottle and closing it. As she gulped down her beverage, Len walked in, sporting an erection. "Is it uncomfortable when it's hard like that?" She asked. "Yeah, but when you started licking it and when we well, 'did it' it felt like I was in heaven." He replied. "Wow. I kinda felt the same way, my cunnie would get wet and I felt like I had an itch inside that needed to be scratched. And my button would get stiff too, kinda like your dick does." Rin explained, using two fingers to spread her lips and looked down at her clit. "You know, it's only Sunday, we don't anything planned for today. Maybe we could spend the rest of the day just... you know." Len said sheepishly, scratching the back of his head. "You mean, just have sex all day?" Rin inquired as she sipped her water. "You don't mind?" He asked. "Hell no! I'd love that! C'mon!" Rin exclaimed excitedly, setting her water bottle on the counter and grabbing Len's arm to drag him back upstairs. "Hey hold on! What's the rush? We could do it down here." Len tried to explain. "Like maybe on the couch in the living room?" Rin asked while tilting her head.   
"You wanna?"  
"Hell yeah I wanna!" 

Rin then dragged him over to the living room couch and had him lie down while she climbed on top of him in a 69 position. "Cool huh? Now we can lick each other!" She said before taking Len's penis in her mouth and began sucking. "Dope." Len said, before shoving his tongue into Rin's snatch. The twins both moaned loudly as they continued using their mouths on each other, Rin licking circles around the glans of Len's dick before sucking on it entirely while Len shoved his tongue in and out of her drenched pussy, practically fucking her with it and occasionally nibbling and sucking on her clit. "Geez Rin, you're so wet." Len commented as he shoved his index finger into her opening and twisted it around. "And you're so hard." Rin retorted as she jacked off his dick and lapped at his balls, sometimes even sucking on one of them. Soon she began grinding her hips into Len's face as her climax drew near. "I'm cumming Len!" She cried out as her juices covered his mouth. "I'm cumming too!" Len cried as he sprayed his cum all over Rin's face. Rin lapped up every drop she could get, although she needed tissues to wipe up all the spunk on her face. After throwing them into the garbage she turned to Len back on the couch. "You ready to go again?" She asked. "You tell me." Len replied smirking as he looked down at his dick. It had gone soft after his orgasm, but now it began to stretch and stiffen again. Rin giggled and straddled him, grabbing his dick and pointing it up to her pussy and slowly lowered herself onto it, moaning.  
"Ahh, so tight!" Len hissed.  
"Ahh, so big!" Rin squeaked.  
And with that, Rin began to ride him again, bouncing up and down, up and down, sucking his dick into her womanhood repeatedly. The twins both moaned and called each other's names as Rin switched it up by rocking back and forth, grinding herself on Len's penis as they locked hands. "Rin you're so hot." Len panted out. Rin chuckled to herself and started talking dirty to him. "Yeah, you love this don't you? You love it when your sister bouncing on your lap, sucking your dick into her hot pussy don't you? I bet you wanna cum and fill me up with your semen. You wanna cum Len? Does Len-kun wanna cum?" "Yes! Yes! I wanna cum in your pussy Rin! It's coming right now! Oh god yes!!!" Len cried, thrusting his dick as far into Rin's pussy as he can and released his seed into her, making his twin cum as well. As they both stopped to take a breather, Rin climbed off Len's softening dick and Len sat up to pull her into a kiss. While they kissed, his dick quickly stretched back out to it's full length, ready for more. Breaking the kiss, Len had Rin get on all fours as he stood on his knees behind her, gave her a good smack on the ass making her yelp before positioning his dick at her entrance again. "Oh my god, we're gonna do it like dogs?" Rin giggled, her face blushing from such a naughty position.

With one hand gripping Rin's hip, and another gripping his erection, Len thrusted into her and went wild, slamming into her again and again as she cries out in ecstasy. Feeling Rin's butt bounce into his crotch with every thrust, Len leaned forward, wrapping his arms around her torso and took her tits into his hands while also kissing and sucking on Rin's neck, leaving a hickey. "Oooh Len, you're reaching so deep inside me I can feel you hitting my womb." Rin moaned out, although they weren't exactly moans, but more like mewls coming from a cat in heat. "Yeah, you like it from behind don't ya? Take it then! Take it! Take it until I explode and drench your pussy in my hot cum!" Len growled out, hammering into her like a piston running at mach 5. Like a bolt out of the blue, Rin's orgasm hit and she screamed as her pussy contracted making Len's orgasm hit as well, his hot cream overflowing in Rin's cunt. Hot and sweaty, the twins fell on their sides as Len slipped out of Rin while they both tried to catch their breath. About 3 minutes later, Len sat up and stretched out his arms before sniffing his underarm and gagging from the musky scent. "Man, I need another shower." He says as he gets off the couch and starts walking to the stairs. "Oh! Lemme join!" Rin calls after him, needing to wash the semen out of her pussy and following his lead. The both of them headed upstairs to the bathroom where Len started the shower head, while Rin grabbed towels for themselves. When the water heat was just right, Len stepped inside, Rin following right behind him.

The siblings both took turns washing each other, Rin getting Len's back, Len getting hers. They then shampooed themselves and took turns rinsing their hair out. After they both shake their heads, making water splash everywhere like a dog would, Len felt his penis stiffen again. "Rin, turn around." He told her. She complies and puts her hands on the wall of the shower and sticks her butt out towards Len while he gets behind her and shoves himself into her womanhood for 5th time that day. "Ahh yes!" She cries out. Len soon starts humping Rin's pussy vigorously, muttering her name with every thrust. "Oh Len, yeah! Give it to me! Harder! Harder!" She says, urging her brother. With her encouragement, Len just completely goes nuts, and absolutely slams Rin's cunt as hard as he could, making the both of them cry out each other's name.

"Rin!!!" 

"Len!!!" 

"Rin!!!"

"Len!!!"

"Ri-ahhhh!!!!" 

"Ahhhh!!!" And with that, they share their biggest mutual orgasm yet, as Len pulls out and sprays his load all over his sister's back. After catching their breath, Rin turns around , and they embrace for another kiss before rinsing off one last time, and stepping out to dry.

End of Chapter 2.


	3. More Sex Before Bedtime

**Summary for the Chapter:**

> How about giving a few More fucks before bedtime?

Chapter 3: More sex before bedtime.

After drying themselves up, Rin turns to face her brother. "What do you wanna do now?" She asked him. "Wanna watch a movie?" Len suggested. "Cool!" His twin replied before dragging him back downstairs. As Rin sat cross legged on the couch, she waited while Len tried to find a good movie for them to watch. "Does 'Kiki's Delivery Service' sound good?" Len asked her. "Oh! I love that movie!" Rin exclaimed happily. Smirking, Len put the blu ray into the machine and then sat next to Rin on the couch. It's about 50 minutes into the movie now and Len was sitting with his leg crossed, while Rin was lying on her side with her head propped up on her arm. "Kiki and Tombo seem like a perfect couple, don't you think so Len?" The female twin asked her brother. "Yeah, they seem cute together." Len replied while shrugging his shoulders. "You think they might, you know, get it on?" He asked her, feeling his dick getting hard for the umpteenth time that day. "Heh heh heh, maybe." Rin replied, giggling. Len smirked and layed on his side behin her. "May I?" He asked. "Oh, well if you insist." Said Rin. With that, Len lifts her leg up and positions his dick at her entrance and then pushes in before sliding himself in and out at a steady pace. "Oh yeah, I don't think I'm ever gonna get tired of this." Rin moans out in ecstasy. "Me neither, God you're so slick inside." Len panted as he picked up his pace, now thrusting harder into Rin's snatch while kissing her neck. "Yes Len! Give it to me! Harder! Harder! Harder!" Rin chanted as she rubbed her clitoris in circles. "Oh yeah, I can feeling coming. Rin, do you want it inside?" Len asked her, feeling his climax approaching fast. "Lemme know when you're ready, I want it in my mouth." She replied while licking her lips. Len nodded, and fucked her as fast as he could go, his balls aching to release his load. "It's ready! Oh god Rin!" Len shouted out before pulling himself out of her. As he sat back on the couch Rin crawled over to him and took his cock in her mouth and sucked until he unloaded his spunk into her mouth. Moaning at the taste, she swallowed it all up, but continued to suck his dick. "Geez Rin, slow down, it's sensitive." Len hissed. She pulled his penis out with a pop. "Sorry, it's just so good." She said before taking it back in her mouth and proceeded to suck it again, as it grew to it's full length. Putting his hand on her head, Len began pulling her down and back up as she bobbed her head, making her deepthroat his dick. "Mmm, moan for me Rin." Len asks her. Heeding her twin's wish, Rin moans as she sucked harder than a vacuum on her dick, the vibrations adding even more pleasure. "Oh you're gonna get it, you're gonna get it, oh yeah you're gonna get it now!" Len yells as his orgasm hits and he cums buckets into his sister's mouth. Swallowing all the spunk that he just dumped in her mouth, Rin smiles at Len. "How was that?" She asks. "Awesome." He replies. The movie had already ended, as the credits were playing now. Len gets up off the couch and goes to turn the player off before putting the CD back in its case. Checking the clock, Len sees that it's now almost 9:00. "I think it's time to hit the hay." He tells Rin as he stretches his arms. "Yeah, I'm a little tired too." Rin relies, yawning. With that, the twins head upstairs and up to their bedrooms. Len removes the covers before climbing into bed, and closes his eyes, ready to enter dreamland. When he's about to nod off, Len feels a sudden weight drop onto his bed jolting him awake. "What the...?" He utters. "Rin, what are you doing?" He asks, recognizing her figure in the darkness.

"I'm sorry Len, I just want sex really really badly. Please? Just one more time?" She begs her brother, pouting. "Aw, how can I say no to that face?" Len flirts. Beaming brightly, Rin removes the covers and straddles Len's waist before taking his once again, erected dick and inserts it into her pussy for probably the millionth time that day. "Mmm, so good." She moans as she bounces up and down on his boner, while playing with her clit again. Len reaches up and cups her A-cup breasts, squeezing them and tweaking the nipples making her cry out. "Oh Len, I love you so much! Oh yeah, oh yeah, oh yeah, make me cum brother! Make me cum!"   
"Oh yeah, ride me good sister, suck my dick into your tight as hell pussy! Take it! Take it! Ride me good until I dump my load into your hot snatch! Oh yeah, fuck me!!!" Len yells out, making Rin ride him faster from his dirty talk while grabbing her ass and thrusting up to meet her bounces in rhythm. "Yeah! Yeah! Yeah! Yeah! YEAH!!! THAT'S IT!!! I CAN'T TAKE IT ANYMORE LEN! I'M CUMMING!!! Rin screams at the top of her lungs as she has her biggest orgasm yet, driving Len over the edge and making him unload the biggest amount of cum he ever made in his life into her cunt. Collapsing from exhaustion on top of her brother, Rin tries desperately to catch her breath, as his cock slips out of her, spunk oozing from her snatch. Len catches his second wind as says: "You know what? Fuck it, we're skipping school tomorrow."


End file.
